标题: 新GRE阅读理解36套每日讨论--33（群178674184） [打印本页] 作者: 普渡哥 时间: 2011-10-9 07:07 标题: 新GRE阅读理解36套每日讨论--33（群178674184） Heat pumps circulate a fluid refrigerant that cycles alternatively from its liquid phase to its vapor phase in a closed loop. The refrigerant, starting as a low- temperature, low-pressure vapor, enters a compressor 5 driven by an electric motor. The refrigerant leaves the compressor as a hot, dense vapor and flows through a heat exchanger called the condenser, which transfers heat from the refrigerant to a body of air. Now the refrigerant, as a high-pressure, cooled liquid, confronts 10 a flow restriction which causes the pressure to drop. As the pressure falls, the refrigerant expands and partially vaporizes, becoming chilled. It then passes through a second heat exchanger, the evaporator, which transfers heat from the air to the refrigerant, reducing the 15 temperature of this second body of air. (126 words)
1. According to the passage, the role of the flow restriction in a heat pump is to (A) measure accurately the flow rate of the refrigerant mass at that point (B) compress and heat the refrigerant vapor (C) bring about the evaporation and cooling of refrigerant (D) exchange heat between the refrigerant and the air at that point (E) reverse the direction of refrigerant flow when needed作者: jojo888 时间: 2011-10-9 09:33
C~~~~~~作者: bennyaaron 时间: 2011-10-9 09:35
c???作者: wyfishhenry 时间: 2011-10-9 09:55
CCC~作者: 普渡哥 时间: 2011-10-9 10:00
确定吗？你们确定是C吗？作者: bennyaaron 时间: 2011-10-9 10:04
不会都错了吧作者: 普渡哥 时间: 2011-10-9 10:06
恭喜你们，都答对了：）